Improving industrial drying process of recycled fine aggregates as a means of carbonation to improve the mechanical properties and plastic shrinkage of self-leveling mortar

Abstract

Industrial drying and carbonation of recycled fine aggregates (RFA) is a highly efficient carbonation method, in which the high temperature and carbon sources generated by drying are utilized to improve the quality of RFA and reduce CO2 emissions. However, there are deficiency analyses in the terms of temperature control and the replenishment of moisture or CO2, during drying process, resulting in the barrier of industrialization application. In this study, physical and mechanical properties of RFA before and after accelerated carbonation treatment were tested and evaluated in different high-temperature drying environments. The results showed that under drying and carbonation at 100 °C, the RFA treated for 2 h demonstrate the best carbonation rate, with three times higher than that of the standard accelerated carbonation. Furthermore, mortars consisted of carbonated recycled fine aggregates (CRFA) show significant improvement in both mechanical properties (compressive and flexural strength increased by 69% and 31%, respectively) and workability. The relationship between physical properties and the performance has been actively explored. The linear relationship between the properties of the fine aggregate and the mortar’s impedance parameters and compressive strength is evident. Noted that, this study proposes an innovative method for industrial drying and carbonating recycled fine aggregates.